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Bioengineering in Urology > Uroflowometry > Flashcards

Uroflowometry Flashcards

1
Q

Define urodynamics

A

Measuring the properties of the bladder for diagnostic purposes

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2
Q

Define uroflowmetry

A

Measurement of flow rate during voiding

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3
Q

Where can uroflowmetry occur

A

Clinical

Home

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4
Q

Most common method of clinical uroflowmetry

A

Gravimetric Flowmeter

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5
Q

Gravimetric Flowmeter

A
  • scales to record the mass vs time
  • jug and funnel above scales which patient voids into
  • in a clinic
  • commode
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6
Q

Units of flow rate

A

Q (m/s)

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7
Q

How to calculate flow rate?

A

Differentiate voided volume in respect to time

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8
Q

Key parameters that are good to know?

A

QMAX = Maximum flow rate
Void Time
Area under curve = voided volume
Shapes of graph = different pathologies sometimes

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9
Q

Artefacts of gravimetric uroflowmetry technique?

A
  • waggle artefact = in men if urine stream is waggled around, can change flow rate instead of straight down
  • differentiation = noise
  • abdominal straining = increasing abdominal pressure, can mask low flow rate caused by obstruction for example
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10
Q

Advantages of Spinning disc flow meter

A
  • to provide faster temporal resolution

- no differentiation = less noise

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11
Q

How does a Spinning disc flow meter work?

A
  • rota turned by an electrical motor
  • turned at a constant rpm (revelutions per minute)
  • individual voids into motor and urine stream slows the motor
  • motor therefore needs more power to turn at same constant rpm against urine stream
  • motor draws more current to turn urine = increased electrical current which is proportional to the flow rate
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12
Q

Why isn’t a spinning disc flow meter used anymore?

A

In practice, advantages of detecting quick changes in flow rate were not clinically useful

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13
Q

Urine drop spectroscopy Method

A
  • urine stream comes down and breaks down into drops
  • drops are assumed to be spherical
  • camera system measures number and diameter of drops
  • this is used to show flow rate over time
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14
Q

Pros and Cons of urine drop spectroscopy

A
  • no differentiation = no noise

- additional problems of cleaning after use

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15
Q

What is the normal QMax?

A

20ml/s

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16
Q

What graph changes will you see during an obstruction?

A
  • Lower QMax (flow rate)
  • Longer void time
  • Same area under the curve if voiding the same volume
17
Q

What is a clinically reduced QMax?

18
Q

What is QMax dependent on?

A
  • bladder volume
  • at very low volumes = QMax is low
  • at high volumes = QMax increased
  • at very high = QMax drops
19
Q

How do you know a low flow rate is caused by obstruction or problems with the detrusor muscle/nerves?

A
  • we don’t know

- need to use cystometrogram/ pressure flow studies

20
Q

What is a cystometrogram?

A

Measuring flow rate as well as pressures in the bladder

21
Q

Advantages of home uroflowmetry over clinical?

A
  • patient voiding in their own setting so no shy bladder/ white coat syndrome/ inhibition
  • can have multiple voids so not relying on a single void measurement (more representative)
  • can record voids throughout the day = better data along with a voiding diary
  • voided volume likely to be more physiological so QMax not dependent on flow volume
22
Q

Disadvantage of home uroflowmetry

A
  • only able to measure QMax, not flow vs. time

- issues of patient compliance/can they use device correctly

23
Q

Stream Test Device

A
  • home method
  • plastic beaker
  • at bottom is tiny few mm diameter hole
  • mainly for men for BPH/prostate cancer diagnosis/monitoring
  • void into cup, urine fills up and flows out at the same time through hole
  • height of urine goes up and reaches maximum height in cup
  • flow rate = flow out of the cup
  • if we measure the height that the urine goes up can estimate QMax
  • cup has indicator line = QMax of 10ml/s, if urine over it then they are fine, if not then they have low flow rate
24
Q

UFlow Device

A
  • home method
  • void into the top
  • hole at the bottom
  • 3 different chambers
  • chambers give 3 different measurements
  • middle = 10-15ml/s
  • lower = less than 10 ml/s
  • upper = 15ml/s
  • different diameters in each chamber = greater change in height for QMax if tube is very narrow, little change in height for QMax if very wide tube
  • so widest at top = we don’t care if normal >15ml/s
  • narrower diameter at bottom as <10ml/s and want to be accurate of flow rate
25
Q

What is the importance of the shape of the urine stream?

A

Spiral (ish) shape as comes up

First length of urine stream is proportional to the flow rate

Bioengineering in Urology (8 decks)

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